1. Field of the Invention:
The present invention relates to a method and an apparatus for recognizing a gripped condition of linens which can be utilized with a hanging type conveyor for conveying linens in a laundry factory, a conveyor for conveying soft products having indefinite shapes such as cloth or film being hung at a plurality of points thereof, or the like.
2. Description of the Prior Art:
Heretofore various types of, conveyors for conveying linens (bed sheets, towels, `yukata`s, etc.) one by one in a laundry factory have been known. By way of example, in a spreader-feeder which is a human-labor-saving machine used after an operator has spread out a bed sheet after washing and dewatering before he throws it into a roll-ironer, a hanging type conveyor is shown for conveying bed sheets after an operator has made moving chucks grip two adjacent corners of a bed sheet (Japanese Patent Publication No. 58-22240).
Now explaining this prior art with reference to FIGS. 31 through 34, in these figures reference numeral 1 designates linens, and illustration is made for the case of bed sheets as representative ones of linens. These linens 1 are spread out by an operator after washing and dewatering, and they are conveyed with their two adjacent corners gripped by chucks 2. The chuck 2 includes a twist spring 23 therein, and a linen 1 is held as pinched between a frame 21 and a lever 22. A bearing 20 is provided at a head portion of the chuck so that the chuck can move freely within a rail 11. Reference numeral 25 designates a weight which is provided for the purpose of balance adjustment. Reference numeral 10 designates the so-called "spreader-feeder" which is an automatic linen spreading and conveying apparatus in which the chucks 2 pinching two corners of the linen 1 and being fed along the rail 11 are separated from each other. Then the chucks 2 are opened under the state where they have spread out the linen 1, and only the linen 1 is conveyed to a roll-ironer by means of a belt conveyor. The chucks 2 after releasing the linens 1 are automatically recovered in this apparatus and discharged along a rail 12.
Reference numeral 11 designates a feed rail for conveying the chucks 2 pinching a linen 1 to the spreader-feeder 10, and if the rail 11 inclines in the forward direction of the gravity, then the chucks 2 would move due to their own gravity. Or else, in the case where the rail 11 is disposed as directed in the direction against the gravity or in the horizontal direction, the chucks 2 are moved as pushed by brackets 15 mounted to a chain 16 circulating in a drive rail 13. A recovering rail 12 serves to convey idle chucks 2 which have released the linen 1, and has the same structure as the feed rail 11. Drive rails 13 and 14 have guides 17 made of resin assembled therein so that the chain 16 may circulate through the guides 17. Brackets 15 made of resin are mounted to the chain 16 at a predetermined distance to push and move the chucks 2 in the feed rail 11 and the recovering rail 12. Also, the chain 16 is circulated by making use of a sprocket 18 or the like. Furthermore, the chain 16 has gap spaces between its rollers and pins so that it can be flexed in the vertical and horizontal directions.
Now description will be made of the operations in the above-described apparatus in the prior art. An operator makes the chucks respectively grip adjacent two corners of linens at an input station to feed them sequentially along the feed rail 11. The linens 1 are conveyed to the spreader-feeder 10 as suspended from the chucks 2 moving along the feed rail 11, by the action of the drive rail or, if the feed rail inclines, by the action of the gravity. During this period, with regard to the chucks 2, for one linen (bed sheet) always two chucks gripping the adjacent corners of the linen must align along the rail 11 in regular sequence. And, in the spreader-feeder 10, the linen 1 is spread out by intaking the chucks 2 two by two as conveyed along the feed rail and separating them horizontally in a sequential manner. Thereafter, the linen 1 is released from the chucks 2, and is transferred onto a belt-conveyor to be conveyed to a roll-ironer. Also, the chucks 2 are collected on a single rail within the spreader-feeder 10, and fed to the recovering rail 12 to be conveyed to the inlet station similar to the linen feeding step.
In the case where linens are transported continuously in a suspended condition with each linen gripped by gripping members such as chucks at a plurality of points, in order to separate the linens one by one or to spread them out, it must be automatically and momentarily recognized which ones of the chucks gripping the linens are gripping a same linen. For instance, in the case of spreading out linens (bed sheets) in the prior art as described above, it is a basic principle that always chucks gripping two adjacent corners of a linen align two by two for conveying the linens, and in the event that one idle chuck not gripping a linen 1, that is, not pertinent to the conveying should mix with the series of chuck pairs, or in the event that one of the chucks 2 gripping the adjacent two corners of the linen should have released the linen, then a problem would arise that the spreader-feeder 10 cannot achieve its normal operation.
Because of the above-mentioned reasons, it is the present situation that always an operator must watch the gripping condition between the chucks 2 on the feed rail 11 and the linens 1. In other words, if it can be automatically and momentarily recognized in the midway of transportion of linens whether or not two chucks 2 being conveyed successively surely grip two adjacent corners of a linen 1, then it becomes possible to reject only the faulty chucks in front of the spreader-feeder 10.